PubSub.subscribe('a', function (event, data) {
    console.log('token1: ' + data.msg);
});

PubSub.subscribe('a.b', function (event, data) {
    console.log('token2: ' + data.msg);
});

PubSub.subscribe('a.b.c', function (event, data) {
    console.log('token3: ' + data.msg);
});

PubSub.subscribe('a.b.c.d', function (event, data) {
    console.log('token4: ' + data.msg);
});

PubSub.publish('a.b.c', {msg: 'hello world!'});

PubSub.publish('a.b', {msg: 'hello world again!'});

